A Modern Approach to Quantum Mechanics · Problem 4.5

A System of Two Spin-1/2 Particles — John S. Townsend

Physics — Quantum Mechanics · spin-half-magnetic-field-probability

Problem

A beam of spin-

\frac{1}{2}

particles in the

|{+z}\rangle

state enters a uniform magnetic field

B_0

in the

x

z

plane oriented at an angle

\theta

with respect to the

z

axis. At time

T

later, the particles enter an SGy device. What is the probability the particles will be found with

S_y = \hbar/2

? Check your result by evaluating the special cases

\theta = 0

and

\theta = \pi/2